The adsorption of phosphate ion onto natural reed ( Arundo donax) was studied in this work. The effect of phosphate initial concentration, adsorbent dose, pH, temperature, and salt addition on adsorption uptake was investigated. The results showed that the adsorption uptake is directly proportional to the phosphate ion initial concentration and inversely proportional to the adsorbent's dose and temperature. A maximum adsorption capacity of 16.2 mg/g was observed at neutral pH. The addition of sodium and potassium chlorides has decreased the adsorption uptake. The adsorption isotherms agree better with the Langmuir model. The negative values of (ΔG) and (ΔH) obtained from the thermodynamic study, indicted that the adsorption process is spontaneous and exothermic. The experimental adsorption data were analyzed using three kinetic models: pseudo-first order, pseudo-second order, and intra-particle diffusion model. The pseudo-second-order model presented the best fit with a determination coefficient ( R²) higher than 0.99 and a minimum normalized standard deviation.

Jordan is facing severe challenges in terms of water scarcity and wastewater management. Thus, there is a growing need for adopting innovative approaches to overcome these challenges. Within the framework of this study, a pilot project was implemented to treat household greywater in rural areas in Jordan with a purpose of reuse for irrigation. The project consists of designing and developing four vertical flow constructed wetland (VFCW) systems located in different sites and integrating them in a decentralized treatment system. The project work aims particularly to present a model of an innovative, compact and effective modified VFCW system. The performance of the systems was assessed by analyzing the quality of the influent and effluent streams through testing 19 water quality parameters. The results revealed that the design was adequate and efficient in treating greywater as exemplified by removal efficiencies of 90%, 90% and 92% for BOD, COD and TSS respectively. Moreover, the other physico-chemical parameters (T-N, T-P, N-NO3-, Turbidity, Ca, Mg, SO4-, and heavy metals) measured in the effluent streams complied all with the Jordanian standards for unrestricted irrigation. Therefore, the outcomes of the current study can be invested to support the use of constructed wetlands in Jordan as a sustainable technology to improve the wastewater management practices and reinforce the decentralized wastewater treatment approach in rural areas. GRAPHICAL ABSTRACT

A non-sacrificial boron-doped diamond electrode was prepared in the laboratory and used as a novel anode for electrochemical oxidation of poultry slaughterhouse wastewater. This wastewater poses environmental threats as it is characterized by a high content of recalcitrant organics. The influence of several process variables, applied current density, initial pH, supporting electrolyte nature, and concentration of electrocoagulant, on chemical oxygen demand (COD) removal, color removal, and turbidity removal was investigated. Results showed that raising the applied current density to 3.83 mA/cm2 has a positive effect on COD removal, color removal, and turbidity removal. These parameters increased to 100%, 90%, and 80% respectively. A low pH of 5 favored oxidants generation and consequently increased the COD removal percentage to reach 100%. Complete removal of COD had occurred in the presence of NaCl (1%) as supporting electrolyte. Na2SO4 demonstrated lower efficiency than NaCl in terms of COD removal. The COD decay kinetics follows the pseudo-first-order reaction. The simultaneous use of Na2SO4 and FeCl3 decreased the turbidity in wastewater by 98% due to electrocoagulation.

A boron doped diamond (BDD) electrode was employed in an electrochemical reactor to oxidize the phenolic content of Jordanian olive mill wastewater. The BDD anode was fabricated using hot filament chemical vapor deposition on niobium and the morphology of the BDD electrode was characterized using an atomic force microscope. Then, electrolysis batch runs were carried out at laboratory scale to test the effect of different process parameters, namely, initial chemical oxygen demand (COD) load (72.9, 33.8, and 0.18 g/L), the addition of Na₂SO₄ as supporting electrolyte, and adding NaCl along with Na₂SO₄, on the efficiency of the treatment process. The results were reported in terms of COD, color and turbidity removal, and pH variation. The experiments revealed that electrochemical oxidation using BDD significantly reduced the COD by 85% with no supporting electrolytes. It was observed that adding Na₂SO₄ with NaCl brought the COD removal to higher than 90% after 7 hours of treatment for COD loads of 72.9 and 33.8 g/L, and after 2 hours for a COD load of 0.18 g/L. Likewise, color was completely removed regardless of the initial COD load. The turbidity for samples with 72.9 and 33.8 g/L as COD load reached a minimal value of 2.5 and 1 NTU respectively.